Web carrier and method of making



March 18, 1952 o. w. BERGLUND WEB CARRIER AND METHOD OF MAKING FiledFeb. 17, 1950 INVENTOR ORION w. BERGLUND ATTORNEYS Patented Mar. 18,1952 WEB CARRIER AND METHOD or MAKING Orion W. Berglund, Dayton, Ohio,assignor to The Orr Felt Blanket Company, Piqua, Ohio, a corporation ofOhio Application February 17, 1950, Serial No. 144,749

4 Claims.

This invention relates to paper making machines and particularly to theendless web or felt that is employed in the machine to convey a wet webof paper pulp from the web forming device to and through the couch andpress rolls, and then to the driers.

Felts that are used on the Wet end of pulp handling machines such aspaper making machines and the like, are notorious for their relativelyshort life, the life of the average wool fabric felt being as little asa few hours under heavy service conditions as in making asbestos board,but seldom extending beyond a few weeks, such as six or seven weeksunder light service conditions as in making tissue papers. These feltsor web carriers are subject to much abrasion and/or chemical action inthe various machines in which they are used according to the nature ofthe pulp being handled and the chemical treatment of the pulp.

In using web carriers on the wet end of pulp handling machines, such aspaper making machines, it is essential that the Webs have a high wettensile strength since they are subject to much stress in the machine.Also, it is essential that the wet web carriers shall allow water todrain freely and rapidly through the web carrier as it passes throughthe various press rolls of the paper making machines. Further, it isnecessary that the Web carriers shall not fill up rapidly with foreignmatter and small fibers of pulp which reduce water drainage through thefelt or carrier. The foreign matter and pulp must be removed regularlyfrom conventional felts in an effort to maintain any degree ofsatisfactory drainage of water from the wet pulp since the speed ofmovement of the pulp web through the machine depends upon rapid waterremoval from the wet pulp. If water drainage from the pulp Web slowsdown, the speed of the machine must be reduced since the carry over ofwater to the driers will be too great for the driers to handle in anygiven time and obtain a determined dryness in the felt.

In manufacturing wet Web carriers for paper making machines and thelike, it is' well-known that only the highest quality wool fibers areused. These are the most expensive wool fibers obtainable and thus thelife of the felts or wet web carriers is a substantial factor in thecost of producing paper and other articles made from wet P p.

It is, therefore, an object of this invention to provide a wet web,carrier or felt for use in paper :making machines and the like whichwill have a greater life, will maintain all the necessary physicalcharacteristics and appearance of the usual papermakers felts that areconstructed from all wool fibers or from wool fiber base materials sothat there will be no change in the character of paper produced on amachine using a felt of this invention and yet has improvedcharacteristics of water drainage and cleanliness not found in otherfelts.

It is, therefore, another object of the invention to provide a wet webcarrier or felt with an improved wet tensile strength and which willwithstand abrasion and chemical action for longer periods of time thanconventional papermakers felts without in any way impairing the rate atwhich water can be removed from the paper pulp through the wet webcarriers.

It is also another object of the invention to provide a wet web carrieror felt which will not fill up with foreign matter as rapidly as theusual papermakers felts, and which will stay cleaner longer, thusrequiring less often cleaning of the felts. By providing such a felt thedown time of a paper making machine is greatly reduced, and in manyinstances prevented entirely, thus providing a definite economicadvantage in the operation of the machine continuously for theproduction of a greater amount of paper in the same length of time.

These and other objects of the invention are accomplished byimpregnating the wet web carrier consisting of a-wool fiber base with aphenolformaldehyde resin solution, preferably an aqueous solution, andcuring the resin in the felt. It has been found that wool fiber base wetweb carriers or felts after treatment with a phenolformaldehyde resinhave a better life, an increase in wet tensile strength and willwithstand abrasion and chemical action for a much longer time thanuntreated wool fiber base felts.

Further, the application of the resin to the felt does not affect orreduce the rate at which water is removed from the wet pulp carried bythe web carrier as would normally be expected by the addition of a resinto a porous material, in fact, the water drainage rate is actuallyimproved, and additionally improves during the service life of the felt.Also, the felts do not fill up with foreign matter as quickly asuntreated papermakers felts, and after cleaning remain cleaner for agreater length of time. The surface characteristics of the felt andfibers therein are improved to prevent accumulation of dirt and foreignmatter by wedging in of the dirt, surface attraction, chemical reaction,puncture and abrasive wear, yet the flexibility of the felt and softnessof the wool fibers is not aifected as to effect the characteristics ofpaper produced thereon. In fact, the phenol reacts with the wool toobtain a physical penetration or impregnation of the wool fibers,resulting in a felt that is not changed as to softness and workabilityfrom an untreated felt, and is just as easy to put on a papermakingmachine as an untreated felt.

These and other advantages are directly attributable to the impregnationof fulled felts with phenol-formaldehyde resin cured in the wet webcarrier or felt. h V

For a full and more complete understanding of the invention, referencemay be had to the following description and accompanying drawingswherein:

Figure 1 is a schematic illustration of a paper making machine on whicha Web carrier 'of this invention is used on the wet end of the machine.

Figure 2 is a schematic cross-sectional view of a Wet Web carrierillustrating generally the construction of such carriers as woven.

Figure 3 is a cross-sectional view of the Wet web ca'rrier illustratingthe compactness of the weave of such carrier after fulling.

Figures 4 to 7, inclusive, illustrate generally the steps of a processfor treating the wet web carriers, in which Figure '4 illustrates afulling step, Figure 5 illustrates an impregnation step, Figure 6illustrates the step of extracting excess resin solution from the felt,Figure 7 illustrates a drying step, while Figure 8 illustrates a step ofcuring the resin in the felt.

In Figure 1 there is illustrated a cylinder type of paper making machinein which web carriers are used on the wet end of the machine forconducting a wetweb of pulp through the various steps of processing thepaper pulp and for conducting the paper pulp to a'drier. Modern papermaking machinery requires high rates of speed of movement of the wetpulp web through the machine to make for eco'nomica1 operation, the pulpbeing adapted to be picked up by a felt or wet web carrier and thenconducted through the machine between a pair of felts for subsequentprocessing.

In Figure 1, therefore, there is shown a paper making machine thatincludes a cylinder mold l that rotates in a cylinder vat II. Thecylinder vat II is supplied with paper pulp in any conventional mannerwell-known to those skilled in the art. I v

A lower felt [2- passes over the cylinder mold ll to'pick up pulp fromthe surface of the cylinder mold, a suitable couch roll l3 beingpositioned above the cylinder mold to cause the lower felt to engage thecylinder mold and to pick up the wet pulp from the cylinder mold. Itwill, of course, beunclerstood that any number of cylinder molds can beplaced in series to obtain paper of different weights.

The lower felt after picking 'up the wet pulp from the cylinder moldpasses over a strain roll l4 and isthen met by an upper felt so thatthewet pulp web will be carried between the upper surface ofthe lower feltl2 and the lower surface of the upper felt I5. The felts l2 and passover light pressing rolls l6 and from there the As many baby presses I!may be used as'desired. From 'the baby press 11, or presses; the paperweb'arid felts pass through the main press I8, or presses.

As the paper leaves the main press I8, it is generally strong enough tocarry itself through the drier I9 which consists of a plurality of usualdrier drums 19a.

The speed of production of a paper web in a paper making machine dependsupon the amount of water that can be removed from the wet pulp web as itpasses through the various presses. The amount of water that is removedfrom the Wet pulp web in turn depends upon the rapidity with which watercan pass through the Web carriers or felts l2 and I5. If the watercannot pass from the wet pulp web, the web will enter the driers with amoisture content that will be too high so that the drier cannoteffectively dry the paper web by the time it leaves the end of thedriers. As the drying of the web is a critical operation, and the webmust leave the driers in a determined dry condition, if too much wateris carried through the presses l1 and 18 in the wet pulp web and intothe driers I9, the speed of the entire machine must be slowed down togive the driers time to drive the excess moisture from the pulp web.

Thus, it is highly important and critical that the web carriers or feltsI2 and i5 pass water rapidly and efficiently to permit the wet pulp Webto enter the driers in as dry 2. condition as possible, thus allowingfor maximum speed of operation of the paper making machine.

The use of Web carriers or felts treated in accordance with thisinvention, in a manner hereinafter described, produces a web carrier orfelt through which Water can pass more rapidly than through conventionaluntreated papermakers felts. In fact, mill operation of felts treatedaccording to this invention, and incorporating the subject of thisinvention, have per mitted increase in speed of operation of papermaking machines as much as 10% without in any way affecting the qualityof the paper produced. Further, in the mill operation it has been foundthat felts incorporating the subject of this invention actuallypermitted water to pass through the felts at a gradually increasing rateduring the life of the felts so that machine operation can actually beincreased gradually asthe felt is used during its service life, thischaracteristic being created in the felt without any loss of othernormal characteristics of the felt which in any way effect the qualityof the paper produce'd'on the machine.

In Figure 2 there is illustrated one general form of construction of awet web carrier or felt such as the felts l2 and I5, as for example thefelt l2. In the felt l2 there is provided a plurality of warp threads 20that are of a wool fiber base or all wool threads. Interwoven betweenthe warp threads are the woof threads 2| to give the desired surfacefinish to the felt; These woof threads 2| are also of a wool fiber base,or of all wool fiber. Many felts are used in an'unnappecl condition, butalso many of them are mapped in a manner illustrated at 22. The felt l2can be Woven on any conventional weaving machine, according to the weavedesired and can be subsequently napped to obtain a desiredsurface finishaccording to the use to which-the felt is put.

The handling of the Wool that'goes into the manufacture of the felt l2through the weaving operation is according to conventional methods ofwashing and carding the wool, spinning the yarn and thereafterweavingfthe yarn into a fabric which forms the felt l2; 'rhewoo'l fibersare therefore in their natural condition without treatment to give themany special characteristics. This is all according to conventionalpractice in the manufacture of papermakers felts.

To produce a felt that is satisfactory for use on a paper makingmachine, the felt is fulled or shrunk in a fulling machine 25 after itis woven,

'as diagrammatically illustrated in Figure 4. In

this fulling or shrinking operation, the felt is placed. in anysatisfactory solution, such as a soap solution, in a tank 20. The feltis caused to pass through an eye 21 which squeezes transversely, thatis, across the width of the felt, to shrink the felt in width. The feltis also pressed through a pair of squeeze rolls 2B and delivered to atrap 29 which bunches the felt together lengthwise to shrink it in itslongitudinal direction.

The apparatus illustrated in Figure 4 is merely illustrative of afulling operation, and this operation can be'carried out in anyconventional fulling machine.

The fulling operation continues until the felt has reached a stabilizeddimensional condition after which no further wetting of the felt willdevelop shrinkage in the felt. Usualy, a felt is woven to approximatelytwice its finished width, the fulling operation shrinking the felt tothe desired finished width and length, and compacts the felt to thecondition illustrated in Figure 3.

After the felts or web carrier has been fulled or shrunk to adimensionally stabilized condition, and properly dried thereafter, thefelt is impregnated with a phenol-formaldehyde resin which is preferablyan aqueous solution. This impregnation may be carried out in any desiredmanner, such as dipping or spraying, but as shown in Figure 5, animpregnating tank 30 is provided to receive the fulled felt 12 forimpregnation. The felt 12 passes through an impregnating solutioncontained in the tank 30 and between the squeeze rolls 31' to obtain athorough impregnation of the fulled felt.

The phenol-formaldehyde solution in the tank 30 may have a concentrationof from to 60%; however, a concentration of from 10 to 25% is preferred.The concentration of the phenolformaldehyde solution can vary over asubstantial range, but the important factor is the resin pick-up of thefelt as determined by the quantity of resin retained in the felt at thetime the felt is subsequently dried and the resin cured therein. Theresin pick-up in the felt shall be from to based on the dry weight ofthe felt, with good average results being obtained when the resincontent of the felt is approximately 5% of the dry weight of the felt.

Preferably, the phenol-formaldehyde is of the water soluble type whichhas an extremely small polymer which permits the resin to penetrate theepidermis of the wool fiber and impregnates the fiber without producingany stiffness in the fiber when the resin is cured.

After impregnation of the felt, excess solution is extracted from it byplacing the felt in a conventional centrifuge 40, such as shown inFigure 6 until the felt has a wet pick-up of approximately 50% ofsolution, depending on the solution concentration, as based on the dryweight of the felt, and. such as will deposit in the felt from to 15% ofresin after curing, based on dry'weight of the felt. Resin contents ofthe felt of from 2 Ao to 15% have been found to be particularlyeffective with a resin content of approximately 5% of the dry weight ofthe felt giving effective results at a commercially economical level.

After the felt is extracted to the desired wet pick-up, it is then driedon a suitable drying apparatus 4|, such as shown in Figure 7. The dryingapparatus may be provided with a heating drum 42 over which the fulledimpregnated felt l2 passes and a drum 43 which acts as a stretching drumto stretch the felt to a predetermined length.

The drum 43 is adjustably carried on suitable supports 44 to adjust thestretched length of the felt concurrently with drying. The dryingoperation is carried out at a temperature well below the curingtemperature of phenol-formaldehyde, and preferably at temperatures offrom 150 to 200 F. to avoid any polymerization of the resin during thedrying operation.

After drying of the felt, the resin may be cured in the felt to a waterinsoluble condition in a suitable curing apparatus, such as thatillustrated in Figure 8.

In the curing apparatus 50 there is illustrated a heating chamber 5|having a drum 52 therein over which the felt l2 passes. A drum 53 ispositioned outside the heating chamber 5| and is adjustably carried onsupports 54. The drums 52 and 53 are suitably driven to cause the feltto pass through the heating chamber 5| a sulficient length of time sothat curing of the phenolformaldehyde resin can be carried out attemperatures of from 225 F. to 320 F., but preferably at a temperatureof 275 F. In the apparatus illustrated in Figure 8 hot air iscontinuously circulated through the apparatus by the blower 60 to obtainuniform temperature distribution in the chamber and air circulationaround and through the felt.

With the felt being cured at a temperature of approximately 275, theresin will cure in approximately 12 minutes, but depending upon thespecific nature of the resin, the curing time may vary from 2 minutes toapproximately 1 hour. Of course, if the curing temperature is reduced tothe lower limit at 225 F., the curing time will increase, and if thecuring temperature is increased to the upper limit of 320 F., the curingtime will be reduced.

The following examples are given to more clearly illustrate theinvention:

Example I A woven, fulled paper making felt was immersed into a 15%aqueous solution of phenol formaldehyde resin sold under the trade nameAmberlite PR-50 until it was thoroughly impregnated. Thereafter the feltwas squeezed between two rolls to remove excessive impregnant and adjustthe resin pick-up to a predetermined quantity. The felt was then curedfor 2 hours at approximately 250 F. and the pick-up of the cured resinwas determined to be 17% with regard to the dry weight felt. The feltthus impregnated with the cured phenol-formaldehyde resin showed anincrease of abrasion resistance to wet condition of over the webabrasion resistance of an untreated felt. Also, the wet tensile strengthof the warp and of the filler threads was increased by 27%.

Example II A woven, fulled felt was treated with an aqueous solution ofphenol-formaldehyde resin solution, which resin is sold under the tradename of Amberlite PR-50, of concentration of 11%,

'Eritrifugedto 'remove excess liquid, dried and Ebdinbie In ghenolforntialdel' yde resin in the form of a 'lj5 aqi1eous solutionwasapplicd to a woven,

'fulled 'paper making felt en eared for 1 hour at ately 230 and "faranother hour 285 The resin pick-up airloijnteii to l2 The set abrasionresistance W S increased as 'lfllich as 390% and the Wet 'tii's'iiestrength 6f the warptiireadsjincreased by 14%; the web tensileisti e'gth' of the filler threads was decreased by esteem;

T e phenbl-forrnaldehyde resinappnea to a fulled iiiolieli wccirasricpacemakers felt produces a papermakers felt that 'hasiniproved tensilestrength in the warp and W601 threads, has improve tear resistance,better fatigue resistsires, greatly improved abrasion resistance, conent' and gradually increasing water drainage throughout thelife of thefelt, and produces a felt that is highly bacteria proof. Even lowperthereafter at aboiit "cei itages of phenol-formaldehyde resin, suchas bfthe'dry'weight' of the felt, added to a felt have bee'ii found togive it good bacteria proofhessJSubsta-ntial elimination of bacterialaction iri a feItmaiiesfbr increased life of the felt siiie the Woolfibers are not weakened by such 'a'tiohthereby allowing the fullstrength of the 5766i libel tob utilized throughout the life of thefiber which life is actually increased by the impregnation with aphenol-formaldehyde resin.

It is'consid'ered that the increased rate of passage "of-"water througha felt treatedfwith a phnol foriiialdehyde resin in accordance withinvention isbrought about by the factrthat resin t'ratm'ent'jof thefulled felt causes the 'woo'lth'reads andfibe'rs t'o maintaintheiroriginal shapeduring the entire life of the felt regardless cf therepeated pressure applications triatare' given t6 the'feltin'its manypassages through the press rolls ofa paper making machine. The high rateof water removal is maintained even though the service life of the feltis usually doubled underimost all condition of operation in a papermaking machine.

This application is a continuation in part application of my co-pendingapplication Serial No. 736,387 filed March 21, 1947, now abandoned.

It will be understood that while there have been described certainspecific embodiments of my invention, it is not intended thereby to haveit limited or circumscribed by the particular details of productproportions, procedures, materials or conditions herein described inview of the fact that this invention is susceptible to modificationsaccording to individual preference and conditions without departing fromthe spirit of this disclosure and the scope of the annexed claims.

Having thus fully described my invention, what I claim as new and desireto secure by Letters Patent is:

1. A bacteria resistant Web carrier for use on 8 wet pulp-handlingmachines to carry wetpulp through the machine consisting of, [a wovenfabric belt having warp and woof threads consisting of a wool fiberbase, said belt being fulled to a predetermined dimensionally stabilizedcondition to provide a support for a wet pulp web with porosity to allowfor free passage of water through the belt from the wet pulp web, and aphenol-formaldehyde resin in and impregnat ng said belt cured in situtherein comprising 2% to 15% by weight of the dry weight of the beltwhich maintains substantially the same free passage of water through thebelt during its service life and resists the action of bacteria on thefelt.

2. A bacteria resistant web carrier foruse on wet pulp-handling machinesto "carry wet pulp through the machine consisting of, a woven fabricbelt having warp and woof threadsconsisting of a wool fiber base, saidbelt, being 'full'ed to a predetermined dimensionally stabilizedcondition to provide a support for a wet "pulp web with porosity toallow for free passage of water through the belt from the wet pulp web,and a phenol-formaldehyde resin in and impregnating said belt cured insitu therein comprising ,4 to 15% by weight of the dry weight of thebelt, said cured resin imparting a bacteria resistant quality to thefelt.

3. In a process of making papermaking felts resistant to the action ofbacteria, the steps of, weaving a fabric felt from warp and woof threadsconsisting of a wool fiber base, fulling the Woven fabric belt to astabilized shrink proof state, impregnating the fulled fabric belt withafph'enolformaldehyde resin solution to deposit in the belt to 15% ofresin by weight based on the dry weight of the belt, andsubjecting theimpregnated fulled fabricfelt to an elevated temperature to cure theresin in situ in the belt to resist the action of bacteria. v

i. A process of making felts for 'papermaking machines and the likeconsisting of, Weaving a fabric felt from warp and woof threadsconsisting of a wool fiber base, fulling the woven fabric belt to astabilized shrink proof state, impregnating thefulled fabric belt with aphenol-formaldehyde resin solution to deposit in the belt to 15% ofresin by Weight based on the fulled'fab r'ic felt to an elevatedtemperature to cure the resin in situ in the belt thereby obtainingwater drainage characteristic through the felt that is rentieredunimpaired throughout the life of the felt'and the felt is renderedresistant to the action of the bacteria. .4

ORION W. BERGLUND.

REFERENCES, CITED The following references are (if record the file ofthis patent: r

UNITED STATES PATENTS Number

